This invention relates to pile cutters and more particularly to a self-gripping scissors-type shear cutter assembly for cutting piles.
Underwater removal of wood piles has always been a difficult problem in waterfront maintenance and clearance projects. Typical pile removal methods are time consuming, hazardous, and often require large support equipment. Removal of wooden piles from waterfront structures during demolition or repair is normally accomplished by one of two methods. The first method is to remove the pile by pulling on it with a heavy crane. This is done by either using the crane to extract the pile until it breaks off at the mudline. This method limits the operation to work locations accessible by crane.
The second method is to physically cut the pile off at the mudline. Blasting, sawing, and shearing are common techniques used for cutting.
Shear type cutters operate by sliding two blades together in either a sliding guillotine motion or scissors type motion. The shear type cutter has several distinct advantages over blasting or the chain and reciprocating saws: since there are no high speed rotating or reciprocating blades, the shear type cutter is safer to operate; if designed properly, the shear type cutter never needs readjustment; wear rate on shear type cutters is low.
However, prior type shear cutters, such as those types used using scissor type blades for tree harvesting purposes have a tendency to slip or squeeze-off the tree during the cutting process and require apparatus with separate clamping means in addition to the cutting blades for gripping or holding the cutting blades against the workpiece during cutting operations. Some commercially available tree shearers are normally mounted for hydraulic operation on a bulldozer and use the weight and mass of the bulldozer to hold the blades against a tree to be cut. For underwater pile cutting a simpler device to prevent squeezing-off is necessary.